In subsea applications, for example, subsea oil production, subsea electrical connectors and penetrators typically provide a connection to the screen or earth of a cable running within an electrical conduit or jumper. Conventionally, the earth connection between a housing of a penetrator or connector and an earth screen of a subsea cable has been of a small cross-sectional area due to circulating earth screen currents being of negligible value because of the lower operating frequencies and currents of applications to date.
FIG. 1 shows an exemplary earth connection between an earth screen 3 of a subsea power cable 14 and a connector or penetrator housing 4. The earth screen 3 of the subsea cable 14 surrounds an inner layer 12, for example, an isolating or semi-conductive material in which one or more core wires are embedded. For example, an earth wire 18 may be soldered to the cable earth screen 3 and attached internally to the connector or penetrator housing at, for example, an earth sleeve 19. An outer boot 20 may surround this termination to prevent water ingress. This kind of earth screen termination is a complex, time-consuming, and highly skilled process. Due to the earth wire 18 having to be routed within the connector or penetrator to be attached to the housing and due to the lack of available space, the earth wire 18 has typically been of small cross-sectional area. Furthermore, the soldering operation may introduce a risk of de-soldering and loss of the earth screen connection at higher temperatures which can be created by a circulating earth screen current and high resistance of the small cross-sectional area of the earth wire 18. Additionally, with the increasing power requirements on more recent and future subsea developments, a main conductor current and frequency may increase, resulting in larger circulating earth screen currents in the earth screen of the subsea cable and consequently between the connector or penetrator housing and the earth screen of the subsea cable. Due to the relatively small cross-section of the earth wire 18, this may result in unwanted higher operating temperatures due to power losses caused by the relatively high resistance of the earth wire 18. Recent specifications relating to subsea high voltage connectors and penetrators have, for example, stipulated that the connecting earth wire must be a minimum of 6 mm2, but should preferably match the cross-sectional area of the earth screen in the subsea cable. Further difficulties may arise by the fact that the earth screen termination has to be sealed and capable of withstanding operational depth pressures of up to 3.000 m in a flooded scenario.
Therefore, there is a need for reliable earth screen connections which provide a low resistance and which can be easily installed and sealed.